From f58b8d0d6abb2477b584547a4e72cc362ecbbcdb Mon Sep 17 00:00:00 2001
From: nicm <nicm>
Date: Mon, 8 Dec 2025 08:04:35 +0000
Subject: [PATCH] Setting working directory after fork means there is a race
 with pane_current_path (especially on platforms with systemd which have to
 take time to do some additional faffing around). To avoid this, change it
 before fork and back in the parent afterwards. GitHub issue 4719.

---
 spawn.c | 39 ++++++++++++++++++++++++++-------------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/spawn.c b/spawn.c
index d06d3969..3b5fae26 100644
--- a/spawn.c
+++ b/spawn.c
@@ -213,7 +213,9 @@ spawn_pane(struct spawn_context *sc, char **cause)
 	struct environ		 *child;
 	struct environ_entry	 *ee;
 	char			**argv, *cp, **argvp, *argv0, *cwd, *new_cwd;
-	const char		 *cmd, *tmp;
+	char			  path[PATH_MAX];
+	const char		 *cmd, *tmp, *home = find_home();
+	const char		 *actual_cwd = NULL;
 	int			  argc;
 	u_int			  idx;
 	struct termios		  now;
@@ -368,6 +370,16 @@ spawn_pane(struct spawn_context *sc, char **cause)
 		goto complete;
 	}
 
+    /* Store current working directory and change to new one. */
+	if (getcwd(path, sizeof path) != NULL) {
+		if (chdir(new_wp->cwd) == 0)
+			actual_cwd = new_wp->cwd;
+		else if (home != NULL && chdir(home) == 0)
+			actual_cwd = home;
+		else if (chdir("/") == 0)
+			actual_cwd = "/";
+	}
+
 	/* Fork the new process. */
 	new_wp->pid = fdforkpty(ptm_fd, &new_wp->fd, new_wp->tty, NULL, &ws);
 	if (new_wp->pid == -1) {
@@ -383,22 +395,23 @@ spawn_pane(struct spawn_context *sc, char **cause)
 		return (NULL);
 	}
 
-	/* In the parent process, everything is done now. */
-	if (new_wp->pid != 0)
+	/*
+	 * In the parent process, everything is done now. Change the working
+	 * directory back.
+	 */
+	if (new_wp->pid != 0) {
+		if (actual_cwd != NULL &&
+		    chdir(path) != 0 &&
+		    (home == NULL || chdir(home) != 0))
+			chdir("/");
 		goto complete;
+	}
 
 	/*
-	 * Child process. Change to the working directory or home if that
-	 * fails.
+	 * Child process. Set PWD to the working directory.
 	 */
-	if (chdir(new_wp->cwd) == 0)
-		environ_set(child, "PWD", 0, "%s", new_wp->cwd);
-	else if ((tmp = find_home()) != NULL && chdir(tmp) == 0)
-		environ_set(child, "PWD", 0, "%s", tmp);
-	else if (chdir("/") == 0)
-		environ_set(child, "PWD", 0, "/");
-	else
-		fatal("chdir failed");
+	if (actual_cwd != NULL)
+		environ_set(child, "PWD", 0, "%s", actual_cwd);
 
 	/*
 	 * Update terminal escape characters from the session if available and